Yea, I do recommend taking it off and rebuilding it. If you haven't done it before, ask the local auto parts guys if they know of anyone... (then you'llbe good for oh, 3-4 yrs) and Kiskadee is right, once you do one yourself, you'll be pizzed at what they charged you.
It is relatively easy to do yourself, if you've got a steady hand, patience, and a significant other that doesn't mind fumes and gunk all over her kitchen. (not everyone has a 24x36 heated shop, eh?)
Barring that, I agree there will probably be a significant layer of
varnish build up.
Don't try to treat this by buying a dozen cans of gum-out at wallyworld. it'll loosen the
varnish alright, and send it down the path, right into "what the hell happened".
If you're going to do a rebuild, THEN clean like a white tornado.
That being said, give her a whack when she's running, that might loosen the crud under the needle.